Dust mop chute

Q: We have an existing 24-inch diameter chute throughout our building that is designed for housekeepers to shake out the dry dust mops into the chute. A ventilation fan takes the dust into a collection bin. The issue with this system is the 24-inch chute is not enclosed with a fire-rated enclosure, and we were told that this chute needs to have an enclosure. What do you say?

A: All vertical openings through a fire-rated floor assembly are required to be protected in accordance with Section 8.2.5 of NFPA 101, Life Safety Code® (LSC), 2000 edition. This pneumatic rubbish chute is no different than any other chute, such as a linen or trash chute, and requires a fire-rated enclosure that extends from the floor to the deck above on each story. Even if the sheet metal duct is sealed tightly around the floor or deck, the thickness of the sheet metal does not have an appropriate fire resistance rating to meet the requirements of section 8.2.5. Since you do not have any fire-rated enclosure now, any enclosure that you add will need to meet new construction requirements. If the vertical enclosure extends to four or more stories, then the enclosure would have to be two-hour fire rated. Otherwise you need to make the enclosure at least one-hour fire rated. Section 19.5.4 of the LSC has these additional requirements for existing rubbish chutes:
• If the chute opens directly onto a corridor, it must have a 1-hour fire-rated door assembly
• The chute must be protected with automatic sprinklers
• The chute collection room can serve no other purpose